40inch tires question

[ldstruckn]

will be ordering a JLUR diesel very soon and planning out the build.
I have had 6 wranglers and cj's in the past so I know alot about lifts, tires, etc.
I am looking into running 40's on the new jeep and I have been researching, with little to no avail, what it will take to run them.
who is running them? what did it take to get the spare to work? steering component upgrades? will the stock rims work or will new rims or spacers be needed with a 3.5 to 4 inch lift? what else am i not thinking of?

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[MarkY3130]

Are you looking to wheel it afterwards or just for looks?

I wouldn’t do it unless I was planning on Dana 60 axles, PSC hydraulic steering, 3.5” complete lift, will require after market wheels for sure (factory wheels aren’t wide enough to mount a tire that wide), bumper mounted tire carrier, etc.

I think it would take $25-30k in parts as a starting point, and then you need to do the labor yourself or pay for that too.

 

[Carlton]

As previously said, really depends on your intentions for the jeep.

Around town:

4 inch lift
Aftermarket wheels with 3.5" or less backspacing
Stubby front bumper
Rear bumper with clearance for tires and a tire carrier
Gears
Programmer

For street use you're looking at $10-15k (plus parts will wear faster so money to fix).

If you rock crawl:
Dana 60s
Hydraulic steering
After market fenders for more clearance

Looking at $25k+

 

[ldstruckn]

seems to be very costly to add 1.5 inches of ground clearance.
I live in colorado and frequent our great trails pretty much monthly; during the really cold months we hit up moab and grand junction.
I may back off and go with 38's and a little extra skid plating.
thanks for the input. My main concern was snapping axles due to the torque of the diesel. I have been wheeling since 1997 and have never broken an axle or gears; I'd like to keep that streak alive.

 

[ThirtyOne]

seems to be very costly to add 1.5 inches of ground clearance.
I live in colorado and frequent our great trails pretty much monthly; during the really cold months we hit up moab and grand junction.
I may back off and go with 38's and a little extra skid plating.
thanks for the input. My main concern was snapping axles due to the torque of the diesel. I have been wheeling since 1997 and have never broken an axle or gears; I'd like to keep that streak alive.

To me Rubicons are built for 35-37. If you go higher than that you may as well buy a Sport and build it. That will save you some money for mods. You are going to replace the suspension, axles, lockers, and gears anyway.

 

[sourdough]

seems to be very costly to add 1.5 inches of ground clearance.
I live in colorado and frequent our great trails pretty much monthly; during the really cold months we hit up moab and grand junction.
I may back off and go with 38's and a little extra skid plating.
thanks for the input. My main concern was snapping axles due to the torque of the diesel. I have been wheeling since 1997 and have never broken an axle or gears; I'd like to keep that streak alive.

IMO, you’ll need expensive upgrades beyond a 3.5 lift. Axles and Hyd. steering too. The diesels torque with lockers and 38’s will twist up stock 44’s and a 38” tire require steering upgrade of all stock components.
If you haven’t seen BriteLite youtube videos, check out the progression of upgrades required on their JLU during the course of their hard/extreme trail running. They have managed to keep it on the road with 38’s but at a cost of $125G +.
I’m not an expert but FYI, I played around on some hard trails with my new JLR before modifying it. I experienced several moderate to hard trails doing EJS Moab, turned around on Chinaman Gulch in Co. during All-4-Fun week and played on most of the Rubicon in Ca. in my stock JLR. I found 5,6,7 rated trails too intense for my liking but got what I was looking for, first hand experience. My new JLR with a 3.6 now has a 3” lift, 37’s and complete skid/armor upgrades just for the ease/peace of mind in doing 4,5,6 rated trails. It is now easy picking a line and great for site seeing while cruising the back trails. I expect those 37’s to cause stress on the suspension and drivetrain overtime but hopefully not break parts. I’ve added all new HD steering linkage. I believe/expect the steering box, ball joints and u-joints will all wear prematurely due to the 37” tires. That is a big tire and big enough, IMO. Extreme trails are for rock buggy’s and business relate folks that can write off expense’s.

 

[Willcbooth]

I’ve been looking at 40’s for when I put my Teraflex long arm kit on. Will go from 2.5” to 3.5” lift then, and replace the axle and drive shafts. I believe for max flex, the pinch seams need to be ground down. If you’re on Instagram, check out @dads_that_wheel
They run 40’s and one of them are on RCV axles with the factory D44 with 4:10s for now. The other wheeled stock axles and gears for a year with 40s. They are hitting Moab next month and driving all The way from Toronto.

 

[Remmy]

I'm really impressed with how well Kevin's (LB) JLR held up with 38s. They pounded on that thing bouncing up slick rocks exc. and it held up well. Can barely remember but it seems they had a Ring/Pinion issue after banging on a slick rocky hill with the Turbocharged 3.6. I believe they were running 5.13s at the time???

At this point that is one of my main concerns as I'm considering RCVs and going to the KM3 39s this Summer. The Patagonias seem like good tires but they just don't to grab as well (in the summer) as my STT Pros. They kick the S#@! out of them on the ice though haha.

I'm willing to run a slightly taller gearset if it means a stronger R/P setup. I would pay for it on the highway, but IMO the 8-speed combined with the 4:1 TC is plenty low for wheeling off-road. 4.88s would certainly do the trick although I would prefer 5.13s.

Decisions Decisions...

 

[ldstruckn]

i remember back when everyone said all these same statements about running anything bigger than a 33 on a dana axle. interesting how times never change.
I was warned repeatedly that running anything over a 33 without 1 ton axles would just lead to failure back in my CJ and TJ days. I have always found that with time these axles prove to be much stronger than thought, unless you have little skill and try to throttle out of every situation. That breaks everything.

 

[JLDIESEL]

I’ll be doing a 3.5” lift with 40s. My buddy (red) is on 2.5” lift and other buddy (gray) is on 3.5” of lift. They wheel their rigs and have had no issues.

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